The present invention relates to a refrigeration device to refrigerate a heat load with a refrigerant, otherwise known as a refrigerator. More particularly, the present invention relates to such a refrigeration device in the form of a fluidized bed food freezer and in which the refrigerant is turboexpanded air. Even more particularly, the present invention relates to such a refrigeration device in which the refrigerant is circulated by a venturi-like device such as an ejector.
The prior art has provided a variety of designs of refrigerators that are used to refrigerate or freeze items. In some refrigerators, a refrigerant is circulated through a forced circulation path to the items, which constitute a heat load, so that heat is transferred from the items to the refrigerant. A particularly advantageous apparatus for effectuating such circulation is a venturi-like device such as an ejector which utilizes the fluid energy of the incoming refrigerant to accomplish such circulation.
In practice, refrigeration is not supplied to a refrigerator at a constant rate due to changes in refrigeration demand. When a venturi-like device is coupled to a refrigerator to produce a required circulation of refrigerant, however, the amount of refrigeration being supplied and the degree of circulation cannot independently be adjusted. Any change in the flow of refrigerant to a venturi-like device will also change the circulation flow produced by such venturi-like device.
The aforementioned inflexibility in the operation of a venturi-like device makes the use of a venturi-like device incompatible with the operation of many particular freezer designs. For instance, in a fluidized bed freezer the circulation is not only used to send refrigerant through a forced circulation path for refrigeration purposes, but also, is used to suspend the items to be frozen in a fluidized bed. If an ejector were utilized to accomplish the fluidization of a fluidized bed freezer, the possible increase or decrease in circulation required by a change in refrigeration requirements would be disruptive to the operation of the fluidized bed. Hence, in a fluidized bed freezer, fluidization is produced by motorized fans which not only consume electricity and introduce a heat load but also add to the complexity and cost of the freezer.
As will be discussed, the present invention provides a refrigeration device that utilizes a venturi-like device in which controls are provided to separately control the circulation produced by the venturi-like device and also, the degree of refrigeration supplied.